Structure for supporting fuel tanks in aircraft wings



Sept- 5 R. MONTGOMERY ET AL 2,407,514

STRUCTURE FOR SUPPORTING FUEL TANK IN AIRCRAFT WINGS Filed July 3, 1943 5 Sheets-Sheet 1 l N VEN TORS.

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P 1946- R. MONTGOMERY ETAL 2,407,614

STRUCTURE FOR SUPPORTING FUEL TANK IN AIRCRAFT WINGS Filed July 3, 1943 5 Sheets-Sheet 2 N mm INVENTORS Robert Montgomery rge W. Schcmz Geo BYdyt Ta A TTORNE Y Sept. 10, 1946. RQMONTGO'MERY ETAL 2,407,614 STRUCTURE FOR SUPPORTING FUEL TANK IN AIRCRAFT WINGS 5 Sheets-Sheet 3 Filed July 3, 1943 INVENTORS Robert Montgomery I CreorqeI/VScheme 3 7 .1

ATTORNEY 5 .10,-1946. MONTGOMERY Em; 24 7, 4

STRUCTURE FOR SUPPORTING FUEL TANK IN AIRCRAFT WINGS Filed July 3, 1943 5 Shets-Sheet. 4

ssiaiiiii Q George W. Schcme.

BY TM.

A TTORNE Y INVENTORS. Robert Montgomery 7 Sept. 10 1946. R. MONTGOMERY 51' AL 2,407,514

STRUCTURE FOR SUPPORTING FUEL TANK IN AIRCRAFT WINGS Filed July 3, 1943 5 Sheets-Shet 5 INVENTORS.

GeorgeW. Schcme (i0 bert Montgomery I Patented Sept. 10, 1946 sTRUcTURE FOR SUPPORTING FUEL TANKS IN AIRCRAFT WINGS Robert Montgomery and George W. ,Schane, Philadelphia, Pa., assignors to The Budd Company, Philadelphia, Pa, a, corporation of Pennsyivania Application July 3, 1943, Serial No. $93,378

This invention relates to aircraft structures,

particularly to the Wing structure of anairplane in the region of a removable fuel tank, and has for an object the provision of improvements in this art. t t

one of the particular objects of the invention is to provide a sturdy mounting for a fuel tank of large capacity in the wing of an aircraft.

Aliiother object is to provide a removable fuel tan v Another object is to reinforce the wing struc" ture to compensate, for the omission of usual structural members in the space Occupied by the tank.

Another object is to provide a strong frame for the opening through which the tank passes during insertion and removal.

, Another object is to provide arig'id closure for the opening and to firmly anchorvt'he closure the opening '50 that it acts as an effectual structural unit with the fixed structure.

Another objectis to provide nose section structure which effectively substitutes for interchord struts in the nose or leading edge of the wing,

Another object is to provide ribs which furnish a convenient and secure anchorage for tank-supporting means. Another object is to effectively transfer skin blanket loads across the tank region.

The enumerated and other objects of the invention will be apparent from the following de scription Iofan ezieinplary embodiment of the invention, reference being made to the accompanying drawings thereof, wherein: I

Fig. 1 is a top plan view of the nose and center sections of an airplane wing in th tank region;

Fig. 2 is a corresponding bottom plan view;

Fig. 3 is a vertical chordwise section through the wing structure with the closure or door removed and the tank in process of being inserted, the view being taken on the line 3-4 of Fig. 1;

Fig. 4 is a similar vertical chordwise section, also taken on the section line 34 ofFig. 1, but showing the tank and door in final assembly position;

5 is aside elevation of a main-section rib elementremoved from the Fig. 4 assembly to show its structure alone; n Fig. '6 is a partial enlarged vertical spanwise section of the lower skin blanket at the door and frame joint, the view being taken on the line t'--t of Fig. "2;

Fig. "7 is a partial enlarged vertical spanwise section "of the upper skin blanket and maina's 'c 7 Claims. (Cl. 244-123) tion rib, the View being V taken on the line 1-1 of Fig 4; g

Fig. 8 is. a partial enlarged vertical spanwise section of the upper skinblanket and nose rib, the view being taken on the line 8.-8 of Fig. 4; V

Fig. 9 is a partial enlarged horizontal section through the rear spar and the adjacent portion of the main-section rib, th view being takenon the line 9.-9 of Fig. 4; and

Fig. 10 is a sectional perspective view of the nose section, the view being taken in approximately the same region as Fig, 3.

The wing in which the tank is mounted comprises a nose or leading edge section N, a main or central section M, anda trailing section T. Only a very small part of the trailing section is shown herein. The main section lies between a front spar-like structure F and a rear spar R. Strictly speaking, the entire nose section con stitutes the front spar but the chord-strut structure which exists at the usual 'front spar location maybe referred to as a spar-like formation. The front spar-like structure is comprised of upper andlow'er span'wise extending L-section chords 23 and interispar struts (not shown but located. be,-

tween thechords at points other than the tank region, which is herein shown). The struts are not shown because the front end of the tank 25 extends through the line where the struts would be located, and other structure is provided in place of the omitted struts The rear spar R in- Icludes'a web 22 upper and lower L-chords 23, and vertical stifiener struts 24. I V

The wing, in addition to thespars F and R, includes (Figs. 1 and 2) other frame elements in the form of main-section ribs 30and aligned nose section ribs 35. A small part of one of the main-' section ribs 30 is shown in Fig. 6. It comprises 2- channel section cap strips or chords 30a, a com- 7 plete web .301), and stiffening struts 300. The wing includes anu-pper cover or skin blanket 46, a lower cover or skin blanket 50, and a nose cover or skin blanket B0. g

The nose blanket is shown to be made up of an upper portion Sea, a lower portion b, and a front closure portion 600. Theskin portions are connected by splice strips 5i. In addition tothe skin sheets proper, the nos blankets 60a and 60b comprise through-running stringers B2.

The main section skinblankets 4 0, 59, besides the skin sheets proper, comprise Y-bulb stringers ll toward the front and rear edges,hat-'shaped Channel-flanged stringers 42 in the middle, and heavier 'hat shaped border "stringers 43 at the extreme "frontand rear edges. In theregions r the Y-bulb stringers 4| the skin blankets are provided with clips 44 for adjustable connection to the ribs; and in the region of the hat-shaped stringers 42 the blankets are provided with flanged clip strips 45 for adjustable connection to the ribs. V

In the tank region the structure is considerably altered, though the general representation of parts remains the same as in typical portions of the wing. Thus there are main ribs, but they are made heavier, of difierent shape, and divided differently; there are nose section ribs, but they are made heavier, of double web's, interconnected and reinforced, and recessed on the rear end to fit the front end of the tank; and the front sparlike formation is Present onlyin the form of the upper and lower'chords which are'connected at spaced points by the nose ribs instead of by the typical inter-chord struts. A portion of the lower skin blanket is omittedto form an opening in sufficient size to pass the tank ther'ethrough. This opening is heavily reinforced around its marginal edges. And a. strongly. constructured closure or door is provided to fill the opening and form a rigid continuation of the'skin blanket and ribs across the opening. Specifically the constructionis as follows: I j

Referring to Figs. 3, rear spar It and theupper chord 2!] of the front spar F at. everyribiTstation there is disposed and secured an L-shaped'rib-strut member 38, r This is a double-webbed me'mbercomprising the parallel' plate web'sv 31a} outer web-connecting ex- 4 running stringers 52. The inner flangededges are arcuately recessed, as at end of the tank 23. -langed lightening holes 336 are provided in the webs. The webs are connected in box-like fashion near, the upper edge by two channel-shapedbars 361, 35g and near the lower edge by two channel-shaped bars 3671;, 35k. At

the upper projecting ends the webs are further connected by a terminal channel-shaped spacer 36m which at the front edge is welded to the upper spar chord 20. A similar channel-shaped spacer 361i is welded between the webs near the mid-height but disposed with the open side outward. A bolt 3'5 passing through a hole in the webs 36a and the bar 3% serves as anchorage for a tank supporting strap 33, Flanged clips 39 attach the webs 36a to the lower spar chord 20. The lower ends of the webs extend beyond the spar chord 28, as does also the end of the bar 36h, to partly underlie the tank andto serve as anchorage for the closurejfor the lower skin blanket opening. The opening'is designated as 4,5, .7, and Q, between the teriorly-flanged channel members 31b (horizontal v longlor .rib L-arm of the rib-strut, transverse stiffening elements 31a for the upper long or rib L-arm, nestedangle-section reinforcing elements 3lf for thevertical short L-arm near the lower end, and inclined stiffeners 3 to in the crotch of the L. The L-shaped rib strut'3l is madewidest in the crotch and diminishes toward the ends in cantile'ver fashion, and interiorl iscurved to fitthe' top and the upper portion of one end of thetan'klfi. :As shown i'nFi'g. 9; the flanges of the 'channel-shaped vertical orstru't member Bic are welded .to the web .22--of thefreaipfspar, the nestinglements 31f also being welded in where present, and one fiangeof the spar stiffening strut 24 also being welded inlwhere present. The outer corner of theL-shaped member 3| is provided with anupwardprojection 3m to connect with the upper chord 23' of the rear'sp'ar and flanged reinforcing plates 3 lie are welded to the webs 31a here. Also in .the corner, flanged reinforcing cleats 3lm are welded to the sides of the webs at athrough-hole for a bolt 32 which anchors a tank-securing strap 33. The long arm of the ribstrut member 3|, that is the rib portion thereof, is connected to the upper skin blanket as usual for the typical ribs. by the clips and the flanged strips,45.. This is shown in Fig, '7. V

A typical nose. rib 35 is shown in Fig. 10. It consists ofafskeletonized flanged web35a and one or more l'connecting struts 35in The rib shown here is an intermediate or secondary nose rib, the typical noseribs which fall in alignment with the typical-main section ribs 33 being somee prise a pair of parallel flanged webs 36a and stiffening struts 33b, Theouter flanged edges are notched, as at 350, to receive the through- EB and the closure or door as 89. I

The forward ends of the rib-strut webs 3hr, or splicers thereof as shown straddle. andare welded to the nose rib webs 33a, 1 g

A'third strap member 63 fills the, space e, tween the strap members 33 andij33 'and'the straps are tightened on the tank by clamp bolts 64 secured between projecting spaced lugs 65' on the straps. v j

The bottom opening 'lllis suitablyreinforced around its edges. At the front edge (Fig. 3) an L-shaped chord H is secured by welding and also by bolts 12 to the lower spar chord 10; At the nose ribs opposite the "clips 39 other clips 13 are provided and the bolts ltexten'd through the flanges of both clips 39 and13as well as'the chords, 2!) andfH. Above the" chords, the" clips 3? and I3 are-secured together through theirflanges by bolts 74, An outer plate l5 is ,w'e'lded across the outerflanges of the chords 2Uand"'|l.

At the rear edge of the opening an Leshaped chord 13 is welded to the lower chord 23 of the rear spar and a marginal'plate I! is welded to the outer flanges of the chords 23 and 'HiLThe r lower end of the strutportion of the rib-strut member 3! is welded in with the chords 2 3 and 16 here.

At the ends (Fig. 6) the stringers 4!, 42, are reinforced by embracing end members Ma interior projecting plates 18a,;outer plates 18b,-v and Z-section' chords 'Hlwelded through their flanges to the plates 18a and'iSb respectively.

I The closure or door 30 comprises a. section of the lower skin blanket 59, including Y-bulb stringers 4 I, middle hat-shaped stringers 4l2, 'marginal hat-shaped stringers 43, rib chord elements 5!, connecting clips fli'andclip strips 4-5.;

At the front and rear edges KFig Bl door is reinforced by L-shaped chords'52 and outer fiat plates 53. Flanged end c1ips54 are' welded to the rib elements 5!, to thestring'e'rs' 43, to the chords 52, and to the skin the flat plates 53.

At the ends'lFig; 6)"the edge reinforcement of the door is similar to thatiat the edge of the opening. .Thus there are stringer embracingen'd members Ma, innerplates 56a, outer-projecting plates 56b, and. Z-sectioned-chords 5 1; welded through their flanges to the platesifimfifib.

The rib chord elements (Fig. 6) comprise the spaced parallel side webs 51a, outer fianged channels 5H). and inner channel member fi lch As shown in Figs. -and 6, ec ured the door is 36d to fit the front by short bolts 8| which pass through theouter projecting flanges of the nested'marginal chord members, and long bolts 82 which pass through the marginal plates of the door and the projecting end of the bar members 3% (at the front edge) and inserted anchorage clips 83 -(at the rear edge). The short bolts 8| are located at short intervals entirely around the door and the long bolts t2 are located at the ribs.

As shown in Fig. 1. a filling opening, closed by a removable cap 84, is provided in the top of the wing; and, as'shown in Fig. 2, a sump opening; closed by a removable cap %5 is provided in the bottom of the wing.

As shown in Fig. 3, the tank 25 is inserted by pushing itsfront end upward and forward over the projecting parts until it seats inthe arcuate recesses in the rear of the nose ribs. Then its rear end is pushed up to fit in the curved crotch of the rib-strut members. Th tank straps 33, 38, and 63 are then connected by the bolts 64. Thereafter the closure 86. is placed in the opening and secured by the bolts 8 l, 82.

The rigid reinforced frame of the bottom opening, the rigid structure of the body and reinforced frame of the door and the numerous securing bolts insure that the wing across the opening is as strong as it is elsewhere. Also the double web ribs and the cantilever construction of the rib-struts insure that the interior frame here is as strong as it is in adjacent parts of the wing.

It is thus seen that the invention provides ample space within the wing for a tank; that the tank can be inserted and removed apart from the wing assembly; and that the wing in the tank region is substantially as strong as in adjacent regions.

While one embodiment of the invention has been described to illustrate the principles of the invention it is to be understood that the invention may have various embodiments within the limits of the prior art and the scope of the subjoined claims.

What is claimed is:

1. A wing construction for carrying a removable tank, comprising, in combination, a nose section, a main section, a front spar-like structure between said sections, a rear spar behind the main section, nose ribs recessed on the rear end adjacent the front spar structure, a tank fitting the recessed ends of the nose ribs, the front spar structure being open intermediate its edges in the tank region to permit the front end of the tank to extend therethrough, one or more L-shaped rib-strut members secured to th front of the rear spar and extending across the top of the main section and being connected to the nose ribs at the front end, an upper skin blanket secured to said rib-strut members, the rear end of the tank fitting a shaped portion on the inside edge of the rib-strut members, straps carried by said nose ribs and said rib-strut members supporting said tank, and a closure secured in a tank-passing opening in the lower part of the Wing.

2. A wing construction for carrying a removable tank, comprising, in combination, a main section comprising rib elements and stringerreiniorced skinblankets secured thereto, the ribs and skin blanket of a portion of the bottom of the Wing being removably fitted as a closure in a tank-passim opening, a nose section comprisingnose ribs and a skin blanket thereon, said nose ribs and main section rib element providing conjointly the interior opening for a tank,

a tank secured therein, and means for securing said closure in said opening to form a rigid continuation of the wing structureacross the opening, said opening extending through the wing surface on one side and being provided at the surface with angle-strip framing and flat outer border plates, said closure being provided with nesting angle-strip framing and flat outer border plates, and said securing means ccactin with said angle strips and flat border plates.

3. A wing construction for carrying a removable tank, comprising in combination a main conjointly the interior opening for a tank, a tank secured therein, and means for securing said closure in said opening to form a rigid continuation of the wing structure across the opening, said opening extending through the wing surface on one side and being provided at the surface on the front and rear edges with L-shaped frame members, on the ends with Z-shaped frame members, and on the outside with flat border strips, said closure being provided with nesting framing of corresponding shape and flat border plates, and said securing means coacting with said frame members and flat border plates.

4. A wing construction for carrying a removable tank, comprising, in combination, a main section comprising rib elements and stringerreinforced skin blankets secured thereto, the ribs and skin blanket of a portion of the bottom of the wing being removably fitted as a closure in a tank-passing opening, a nose section comprising nose ribs and a skin blanket thereon, said nose ribs and main section rib elements providing conjointly the interior opening for a tank, a tank secured therein, and means for securing said closure in said opening to form a rigid continuation of the wing structure across the opening, said opening extending through the wing surface on one side and being provided at the surface framing, the ribs of the upper part of the main section being extended down at the rear end of the main section as struts to the lower part of the wing and being connected at the lower end to the frame members of the opening.

5. A wing construction for carrying a removable tank, comprising, in combination, a main section comprising rib elements and stringerreinforced skin blankets secured thereto, the ribs and skin blanket of a portion of the bottom of the wing being removably fitted as a closure in a tank-passing opening, a, nose section comprising nose ribs and a skin blanket thereon, said nose ribs and main section rib elements providing conjointly the interior opening for a tank, a, tank secured therein, and means for securing said closure in said opening to form a rigid continuation of the wing structure across the opening, the tank.

securing means including suspension straps attached at their upper ends to the upper portion of said ribs.

6. A wing construction for carrying a removable tank, comprising, in combination, a main section comprising rib elements and stringerreinforced skin blankets secured thereto, the ribs and skin blanket of a portion of the bottom of the wing being removably fitted as a closure in a tankpassing opening, a nosesection comprising nose ribs and a skin blanket thereon, said nose ribs and main section rib elements providing conjointly the interior opening for a tank, a tank secured therein, and means for securing said closure in said opening to form a rigid continuation of the wing structure across the opening, said opening extending through the wing surface on one side and having its front and rear edges at the wing surface reinforced by angular spar chords, by angular frame members secured thereto, and by flat border strips on the outside, the opening having its end edges reinforced by stringer-embracing elements, by flat plates on the inside and outside, and by Z-section members whose flanges are secured to the flat plates, the closure being reinforced on its front and rear edges by angular frame members and by flat border strips on the outside, the closure having its end edges reinforced by stringer-embracing elements, by flat plates on the inside and outside, and by Z-section members whose flanges are secured to the flat plates, and said securing means coacting with said reinforcing means.

- '7. A wing construction comprising, in combination, an interior frame and upper and lower skin blankets, the blankets including spanwise extending stringers, the frame comprising front and rear spar means and rib elements secured thereto and having an interior tank space and the lower skin blanket having an opening, a tank disposed in said space, the tank being insertable through said opening, said opening having a reinforcing frame, and a closure for said opening forming a continuation of. the skin blanket and having stringers forming a continuation of the skin blanket stringers and rib elements forming a continuation of said frame rib elements, and said 010. sure having a reinforcing frame, the reinforcing frame at the ends of the opening and the closure comprising members embracing the ends of the stringers, outer and inner plates secured to opposite sides of the skin blanket, and Z-shaped members secured through their flanges to said plates.

ROBERT MONTGOMERY. GEORGE W, SCI-IANE. 

